Do not attempt to turn it on, do not use a hair dryer on it as that could damage the internal components. Your safest bet would be to put the phone inside a bag with a bunch of uncooked raw rice as the rice will absorb moisture as it comes in contact with it. You could also use silca gel packs. You would leave the phone in there for a few to several days until there appears to be no sign of moisture and then you would attempt to power it on.
After powering it up you'll need to back up any important files you have on it as it may still be damaged to the point that it may randomly fail or not function properly, the internal battery may also have been damaged.
Another option is to take it to a phone repair store.
